The Best Bluetooth Kits for Every Car Stereo

If you’re driving an older car and want to be able to jam out to your tunes and make calls over your car’s speakers without installing a new head unit, you have a few options. Over the past four years, we’ve spent more than 50 hours testing dozens of units across the three main styles, including five new models this year. We recommend the Anker SoundSync Drive as the best overall solution for most people—as long as you have an aux-in port, it’s the way to go. But we also have picks for other setups.

Last Updated:
One year ago

Since we named Anker’s SoundSync Drive as our top pick, we’ve seen it go out of stock several times. Anker has confirmed that the model is current; the company is struggling to keep up with demand. We'll continue to monitor the availability of all our picks.

One year ago:
Our current top pick for aux-in kits—the iClever Himbox HB01—has been replaced by the HB01+. We recently tested the newer version, and we will not be recommending it. We’re wrapping up an update to this guide, but if the older HB01 is out of stock and you need to buy something right now, our new top pick will be the Anker SoundSync Drive.

One year ago:
Our top pick for Aux-in kits—the iClever’s Himbox HB01—is currently unavailable on Amazon. It has been replaced by the HB01+, which has three USB ports instead of two, uses Apt-X, a longer cord, and works with both Siri and Google Now. We’re calling in the upgraded model for testing, but for now we recommend a previous pick—the GOgroove SMARTmini AUX—which we still discuss in the Competition section.

Two years ago:
We tested several new aux-in models and added them to the Competition section. We also removed our line-in pick for multiple phones since that feature is included in our main pick from iClever.

Three years ago:
If your vehicle has an auxiliary input, we recommend using the iClever Himbox HB01 because of its superb audio quality and mic performance. It’s easy to set up too and automatically connects when you start your car. We have other options if you need to pair multiple devices or don’t have an auxiliary input.

Three years ago:
We're working on a new version of this guide, but we also saw something new from Griffin at CES. They took the wraps off the diminutive iTrip Aux Bluetooth, a $50 audio accessory that plugs into a head-unit auxiliary port while drawing power from a vehicle’s 12-volt cigarette lighter. It’s more expensive than our current aux pick, but we’ll have a look at it to see if it’s worth the the extra cash.

Three years ago:
We've put several more hours of research and testing into this guide, and we're getting ready to name some new picks in a few weeks. Setting this to wait status for now.

Three years ago: An updated version of the Kinivo BTC450 is now available. The BTC455 keeps all the same features as the BTC 450, but includes the ability to connect to two Bluetooth devices at the same time. It's $45, but the ability to connect two devices is interesting. We'll have to test it to see if we're able to overlook its other shortcomings.

If you have an auxiliary-audio input (aux-in) jack, you’re in luck, because aux kits are the most-reliable and best-sounding way to add Bluetooth to your car. We recommend Anker’s SoundSync Drive because it has great sound quality while playing music, and sounds more intelligible during phone calls than any other model we tested. Its microphone produces a clearer-sounding voice on the other end than any of the options we tested. The other devices we considered all sounded muffled, but Anker’s aggressive noise and echo cancellation made voices easier to understand—even with the windows down, driving at 50 mph. Unlike some competitors that have a permanently attached power adapter that monopolizes your car’s accessory-power jack, the SoundSync Drive works with any USB power source, such as a USB charging port in your car or a standard USB car charger. (While no charger is included, the Anker is about $10 cheaper than the next-best model.) To use it, simply stick it to your dashboard with the included adhesive backing and press the big button to turn it on whenever you turn on the car. We would prefer it if it turned on and connected automatically, but the Anker’s superior voice quality and lower cost ultimately won us over. However, if you prefer automatic connection (or if you need the ability to pair two phones at once), we have a pick for you, too.

Voice performance isn’t as strong as with the SoundSync Drive, but the HB01 lets you pair two phones and comes with a charger—at a higher price.

If you share a car and need to be able to pair multiple devices—say, two phones—with your Bluetooth car kit, iClever’s Himbox HB01 is the best option. (Note the lack of a “+” at the end—the HB01+ is a newer model we don’t like as much.) Our previous top pick, the Himbox HB01 pairs with two devices, includes a charger, and can be removed when not in use thanks to a magnetic connection. However, it’s voice quality isn’t as good as the SoundSync Drive’s and it costs more.

While it will work for voice calls, this FM transmitter is best suited for music streaming. The design allows you to see which station you’re tuned to and manually (but easily) find a new one if necessary.

If your car’s audio system doesn’t have aux-in and you value music streaming over call quality, get the GoGroove FlexSmart X2 FM transmitter. It works in any car with an FM radio and an accessory-power outlet (nee cigarette lighter). It automatically connects with your phone when you turn on the car. In our testing, it consistently provided a radio signal as strong as or stronger than any of its competitors. It doesn’t have auto-scan (the capability to automatically tune to what it believes to be the most open station in your area), but it does have an easy-to-turn tuning dial that we found worked much better than any of the auto-scan features we tested on other units—we were able to find a better frequency manually. Plus, it sounds as good as an FM transmitter can. In fact, after doing a side-by-side comparison with a direct aux-in connection, my ears struggled to hear a difference. Most FM transmitters are only so-so at best, but the FlexSmart X2 is actually good.

The Roadster 2 is easy to use while driving, sounds crisp and clear, supports a few voice commands, and includes a built-in motion sensor.

If you don’t have an aux-in jack, and you value call quality over music streaming, get the Motorola Roadster 2 speakerphone. It’s the best car speakerphone we’ve found, offering not only the ability to make clear calls, but also a passable (though far from excellent) FM transmitter so you can play music through your car’s radio. Unfortunately, the Roadster 2 won’t automatically pair with your phone when you start the engine, because you need to turn it on separately. This can be tedious, but it’s common for battery-powered devices.

Who is this for?

These products are for people who have an older car and want Bluetooth connectivity for music and phone calls without the hassle or cost of a brand-new stereo or professionally installed kit. They let you stream music from your smartphone or other Bluetooth-enabled device to your car stereo, and they let you answer calls in the car, listening to call audio through your car’s speakers.

You basically have three options: a BT receiver with an auxiliary-audio output, a BT receiver with a built-in FM transmitter, or a Bluetooth speakerphone.

Which type should I get?

None of the options are perfect—depending on which system you choose, you’re going to have to either sacrifice your car’s accessory-power outlet, or get something that needs to be recharged regularly—but they’re portable, inexpensive, and relatively hassle-free. And while they might not always sound as good as a car stereo with built-in Bluetooth, one of these will more than suffice until you’re ready to upgrade your car or its stereo.

If you have a car with an auxiliary-audio input jack (basically a line-in headphone jack), get an aux-in kit. These devices are small, easy to use, and let you control music and phone calls right from your phone with just one or two buttons. And because they connect directly to your car’s stereo, aux-in kits offer the best sound quality for phone calls as well as music.

An aux-in jack on a Toyota Prius C.

Depending on which system you choose, you’re going to have to either sacrifice your accessory-power outlet or get something that needs to be recharged regularly.

If you don’t have an aux-in port and you’ll be listening to music streaming more than taking phone calls, an FM transmitter is a solid option. FM transmitters usually have issues with static and interference, but we’ve found a great-sounding one that offers an unusually strong connection. Call quality won’t be excellent because the microphone on these units usually can’t be moved to an optimal location, but music or podcasts sound very good. (In the past, we recommended—assuming your older car had a cassette deck—a cassette adapter and miniplug adapter and then using our aux-in pick, but our FM transmitter pick offers music-streaming sound quality that’s just as good as that of an aux kit.)

Finally, if you have a car with no aux-in jack and you value call quality over music quality, get a dedicated speakerphone. Speakerphones are super portable and come the closest to creating a true hands-free-phone experience, making them ideal for phone conversations. The better ones, like our pick, also include a built-in FM transmitter and the capability to control music, answer phone calls, and send text messages without having to touch your phone. However, it’s not ideal for music streaming—its built-in speakers don’t sound great, and its FM transmitter is weak.

How we picked and tested

We began by reading reviews for as many devices as we could find. CNET and PCMag are among the few places you can find reviews of Bluetooth car kits (and even then, the reviews on those sites tend to be years old), so we also read Amazon user reviews, which are more recent and generally numerous. But whether the product was an aux-in kit, a speakerphone, or an FM transmitter, the most important thing we looked for when testing was ease of use and how close any kit came to a native Bluetooth experience in your car. With that in mind, we set out to find the most promising testing candidates for each type of kit.

Aux-in kits are cheap and plentiful; Amazon sells hundreds of no-name brands offering their take on the style—or at least slapping their name on someone else’s design, with the same features for approximately the same price. With that in mind, we limited our most recent sweep to brands our editors have actually heard of. That’s admittedly not the most important criterion for limiting a model list, but it’s a necessary one considering the sheer volume. With one exception (that ended up being a pick), we eliminated any kit that required the car’s accessory-power outlet for juice but didn’t include a USB charger with at least a second 1-amp USB port for charging your phone. We also eliminated any models that lacked phone-answering functionality, as well as those that had awful user reviews.

FM transmitters were easier to narrow down because not many companies make them, and among the ones that do, GoGroove and Mpow are the only brands that have garnered user reviews good enough to warrant checking out.

Bluetooth speakerphones used to be far more plentiful, but their popularity has waned dramatically over the past few years as the speakerphone features in smartphones have improved. We’ve always looked for speakerphones with built-in FM transmitters, auto-reconnect features, and native voice commands. After a research sweep this year, we found no new models that warranted testing.

We conducted all testing for this update and the previous one in a 2013 Toyota Prius C with an auxiliary-audio input. To avoid possible interference and crossed signals, we didn’t pair our test phone—the Moto X Pure (2015)—with the car’s Bluetooth.

We tested outgoing call quality and sound clarity by using each unit to leave voicemails while driving down the highway at about 55 mph. For each product, we recorded a voicemail with the windows up and then another with the windows down; we then pulled over and switched to the next unit. We then distributed the audio files for these voicemail messages to a panel of Wirecutter editors and writers, who ranked them and left comments on audio quality.

After looking at 21 competitors over four rounds of testing, the Anker SoundSync Drive is the best aux-in kit we’ve tested. Sound quality while streaming music is as good as or better than that of any other model; it sounds better when making phone calls; and we appreciate the inclusion of track-control buttons on the main unit. The SoundSync Drive also provides a way to physically activate Siri or Google Now.

Music sound quality is top-notch compared with other aux-in kits—I didn’t experience any buzzing or interference across the volume range. Similarly, we found the quality of the SoundSync Drive’s outgoing voice quality to be better than that of the other units we tested. Its built-in echo and noise cancellation is very aggressive, which leads to a bit of a shriller sound on the receiving end, but voice is clear and understandable—the other models we tested sounded muffled, as if we were speaking through a pillow. This was especially true when the windows were down: The rest of the models tested were borderline unintelligible whereas the sample recorded by the SoundSync Drive was easily understood—if a bit tinny sounding.

The SoundSync Drive has the same general design as all but one of the systems we tested. Its main body is a 1.8-inch-diameter, 0.4-inch-thick (roughly the same size as most of the competition) black-matte-plastic disc with an integrated cord coming out of the bottom that terminates in a standard USB-A plug. A large central button on the disc serves as the main control, the disc also hosts two other buttons for skipping tracks, and a microphone. The disc attaches to your car’s dash with an adhesive sticker. After initial pairing with your phone, it will instantly connect to your phone with a single push of a button. We’d prefer if it automatically turned on and connected whenever the car is started, but it’s not quite a dealbreaker given its advantages in voice quality and cost. Once the SoundSync Drive connects, music-playback controls, phone functions, and voice controls work as expected.

Unlike every other aux-in kit we considered, the SoundSync Drive doesn’t come with a charger. Instead its charging cable can be plugged into any car charger or built-in USB port in your car. This would generally count as a strike against the Anker unit, but its price is commensurately lower and there are great, affordable car chargers that you can easily pair with it—including ones that have 4-plus ports so you can power the aux kit while simultaneously charging multiple devices.

Flaws but not dealbreakers

Some people would understandably prefer that the SoundSync Drive include a charger, but we don’t see this as a major problem because it gives people who already own a charger the option of saving some money. And if you do need a charger, for less than the price of other car kits, you can pick up the SoundSync Drive anda great car charger. Besides, most of the bundled chargers don’t have enough juice to simultaneously charge multiple devices at full speed.

Most other Bluetooth aux-in kits use a magnetic pad for sticking to the dash, which is better if you’ll be moving the unit from car to car or are worried about theft (so you can store the unit out of sight). It would be great if Anker took a cue from the competition on this front, but the advantages it offers in sound quality make this drawback acceptable.

The SoundSync Drive also lacks support for pairing multiple devices at once. If you’re looking for any of these three features, we suggest going with iClever’s Himbox HB01 next.

Voice performance isn’t as strong as with the SoundSync Drive, but the HB01 lets you pair two phones and comes with a charger—at a higher price.

If you need to be able to pair with multiple devices, such as two smartphones, the iClever Himbox HB01 is a good alternative to the Anker. (The HB01 is different from the HB01+, which isn’t as good.) The HB01’s audio quality is comparable to the Anker’s, and we appreciate the inclusion of track-control buttons on the main unit and an extra charging port on the included power adapter. Most important, the HB01 can pair with two phones at once. We also like that it can be detached from its own charger to be used with one that charges your phone more quickly. The Himbox’s small, unobtrusive design is nice, and it comes with a magnetic plate mount that allows you to easily remove the receiver from the dash to protect against theft.

However, the HB01 wasn’t as good as the Anker model in our voice tests—none of our listening panel ranked its audio as the best in either the windows-up or windows-down tests—and the HB01 is more expensive than the SoundSync Drive, so we recommend it only to people who truly need to pair it with multiple devices.

What to do if you have a whiny audio cable

If you’re hearing a whine with the audio cable plugged into your car’s aux-in jack, as we have with some units, you’re not out of luck. This is likely due to radio-frequency interference from your car or even your USB charger, and a ground-loop noise isolator such as this one (the highest rated model on Amazon) should help eliminate the buzzing. However, some reviews complain that the isolator may also reduce volume and/or bass response.

While it will work for voice calls, this FM transmitter is best suited for music streaming. The design allows you to see which station you’re tuned to and manually (but easily) find a new one if necessary.

An FM transmitter takes your phone’s Bluetooth audio and transmits it to your car’s stereo using FM-radio transmissions, so it works with any head unit. After going hands-on with seven of the highest-rated FM transmitters around, we’re confident that GoGroove’s FlexSmart X2 is the best because it sounds as good as or better than the competition when tuned to the same stations. In fact, the FlexSmart X2 not only sounded better than other FM transmitters, but I struggled to discern a difference in audio quality when comparing it head-to-head with a direct aux-in connection from my phone to my car’s stereo. (Of course, to get that clarity, you need a clear FM frequency, which isn’t always available, especially in urban areas.)

You insert the FlexSmart X2’s 3.5-inch-long base into your car’s accessory-power outlet; a 4-inch-long, flexible gooseneck extends up from the base to hold the unit’s control module. This module has track-control and play/pause buttons, buttons for answering and disconnecting calls, an FM tuning/volume dial, a screen that displays the current transmission frequency, an aux-in port, and a 1-amp USB port for charging your phone.

After extensive real-world testing, we determined that it’s better to be able to manually tune than to rely on an auto-scan feature that may not be delivering the best station.

The X2 also has an auto-scan feature that claims to automatically find the best (read: clearest) FM frequency for transmission in your area. After extensive real-world testing, we determined that it’s better to be able to manually tune than to rely on an auto-scan feature that may not be delivering the best station.

With the FlexSmart X2, each “notch” of the tuning dial moves the broadcast frequency (station) up or down one decimal number (for example, from 97.4 to 97.5), rather than the more-common approach of browsing odd-numbered frequencies; still, it doesn’t take long to get to a particular frequency. Compare this with the FlexSmart X3’s auto-scan feature, which automatically picks a frequency for you at the press of a button (with subsequent presses finding the next “available” station): It might hit on a good, open frequency, but in our testing, it was just as likely to not. In fact, it picked a handful of even-numbered stations (98.2, for example) that aren’t even accessible in the United States. The FlexSmart X2’s tuning knob also lets you easily change frequencies without taking your eyes off the road. Ultimately, we preferred the X2’s granular, easily accessible control to the promise of convenience.

The FlexSmart X2’s FM transmitter also performed comparably to the one on our previous pick, the Mpow Streambot Y, when it came to the strength and clarity of its signal. Comparing the two directly, using the same iPhone 6s Plus as the source device, the same music, and the same FM frequency in the same location, both streamed music with practically no interference. They also provided the best audio fidelity of any of the units we tested—as good as a direct aux-in connection, which is surprising considering the usual quality of FM transmitters. As long as you find a good (clear) station, you’ll be impressed with the results.

Our main reason for switching our pick from the Streambot Y to the FlexSmart X2 is voice quality. Voicemails left using the GoGroove model sounded better in both windows-down and windows-up tests. That’s not to say outgoing audio was perfect—or even great—but the X2 was the clear winner. We also like that the X2 has multi-point pairing (so you can connect two phones at once), a power button, an aux-in jack for use with non-Bluetooth devices, and an arguably nicer overall design.

The Roadster 2 is easy to use while driving, sounds crisp and clear, supports a few voice commands, and includes a built-in motion sensor.

If your main in-car Bluetooth use is making and taking phone calls, a dedicated Bluetooth speakerphone is the way to go. After testing three of the top-rated speakerphones, we found that the Motorola Roadster 2 is the easiest speakerphone to use while driving and comes the closest to feeling like a native Bluetooth setup. It offers easy pairing with your phone, clear and crisp audio through its built-in speaker, a few native voice commands, and built-in motion sensors that can detect whether you’re in the car. This was enough to earn our praise and be our pick, as well as earn an Editors’ Choice award from PCMag.

The Roadster 2’s design is sleek and efficient. Measuring about 3.5 inches long and 2.8 inches across, the entire speakerphone is roughly the size of a deck of cards, although a bit wider and about half the thickness, allowing it to sit unobtrusively on your car’s visor until you need it. But while the speaker is small, it is powerful.

Incoming audio is crisp, clear, and distortion-free, even at the highest volume setting, which is pretty darn loud. In our testing, the quality wasn’t good enough to make us forget we were using a speakerphone, but it was certainly clear enough to be easy to understand. This is partially due to Motorola’s echo-control and noise-cancellation technology, which is surprisingly effective at minimizing (in the outgoing audio) background wind noise and other interfering sounds that come up while driving. And while the Plantronics unit we tested has similar audio quality, it lacks the Roadster 2’s intuitive physical controls and has a shorter battery life.

In our voicemail test, messages left using the Roadster 2 had the clearest sound. Again, while audio sounded a little speakerphone-like, outgoing voices carried loudly and clearly with little to no interference, distortion, or echo. Even while driving with the windows down at 45 to 50 mph, voicemail audio was loud and clear with little discernible wind noise in the background, which is quite impressive considering the speakerphone was mounted on the car’s visor right next to an open window.

Voice commands are also implemented well. When receiving an incoming call, the Roadster 2 announces the name of the caller if it’s someone from your contacts; otherwise, it recites the phone number. You can say “answer” to take the call or “ignore” to send the call to voicemail. In addition to these device-specific voice commands, you can activate your phone’s own voice commands (Siri on an iPhone or Google Now on an Android smartphone) by tapping the voice-dial button. The Roadster 2 also sports dedicated buttons for mute, call answer/end, FM frequency (more on this below), and music play/pause. (Regrettably, as with many of the Bluetooth kits we tested, you don’t get buttons for skipping tracks, though we doubt most people will use the Roadster 2 for music playback.)

Even while driving with the windows down at 45 to 50 mph, voicemail audio was loud and clear with little discernible wind noise in the background.

The Roadster 2 also offers the best battery life of the speakerphones we tested, with up to 20 hours of talk time and up to three weeks of standby time. The battery level is conveniently announced each time the speakerphone is powered on, though we couldn’t find a way to check the level during use. The unit also has built-in motion sensors that put the Roadster 2 into standby mode once you leave the car (or your handset goes out of range), so you don’t have to worry about draining the battery if you forget to power the unit off when you get out of the car.

If you have an Android or Blackberry 4.5+ device, you can take advantage of Motorola’s Car Finder and MotoSpeak app, which aim to give you an even more feature-rich experience. The Car Finder app remembers the location at which the speakerphone is disconnected from your phone—presumably when you left the car after parking—so you can easily find where you parked. Unfortunately, we had limited success using this app with an LG G2, but it was a nifty feature when we could get the app to work.

The MotoSpeak app takes the hands-free experience a step further by reading incoming text messages and allowing you to dictate outgoing ones without ever having to touch your phone. When you receive a text message, the speakerphone sounds an alert and then calls out either the name of the person who sent the text (if they are in your contacts) or the number the message is from. You can then respond “yes” or “no” to listen to the message.

Unfortunately, the app breaks down when it comes to dictating responses: We weren’t able to successfully dictate a single outgoing message; even a simple “hello” failed to send. (Google Play reviews indicate that other people have had the same experience.) But even though the app is far from perfect for sending texts, being able to have your text messages read aloud while driving is a pretty useful feature to get from a free app—there’s something to be said for being able to legally text and drive, after all.

Predictably, the only feature of the Roadster 2 that left us really disappointed was the built-in FM transmitter. While it was easy to use (a simple press and hold prompts the Roadster to audibly speak a frequency for you to tune your car stereo to), the transmitter itself is not very powerful: We were forced to rescan for a new frequency every few minutes to get a clear signal. We tested the Roaster 2 in the city of San Diego, where there are very few open frequencies, so there’s a chance the transmitter may be more effective in less-dense areas. But even when you get a clear signal, bass performance isn’t as strong as with a direct aux-in connection. Overall sound quality, however, is acceptable.

Few people review car speakerphones regularly, but PCMag called the Roadster 2 “a full-featured, Bluetooth speakerphone that delivers on both performance and ease-of-use.” It also earned an Editors’ Choice award at the same publication thanks to its “truly innovative features.”

The competition

Aux-in kits

For the 2016 update to this guide, we tested three new aux-in kits that didn’t make the cut. The charger included with Mpow’s Streambot didn’t work, and we heard a whine over our car stereo when using iClever’s Himbox HB01+. Aukey’s Bluetooth Car Kit didn’t have such obvious problems, but it simply didn’t sound as good as the SoundSync Drive.

The GoGroove SmartMini Aux was a previous top pick because it has great call and sound quality and a built-in battery. Instead of a round central unit that attaches to your dash, it consists of a small dongle that you can either plug directly into the aux input (if that input is close enough to the driver’s side of the car) or mount on a small Velcro pedestal that you can then attach anywhere on the dash. However, the single-button interface can be a bit confusing, and although battery life is decent (up to six hours on a single charge, according to the manufacturer), you must provide your own car charger, which adds to the overall cost. This is excusable for the superior SoundSync Drive, but the SmartMini simply isn’t as strong of a contender.

Avantree’s Cara II initially struck us as a pretty good alternative to the Himbox when the latter was our pick. Selling for about $40, it’s in the same price category as the other units we tested, but it’s a wider, thicker disc. Instead of using an integrated charging cord, it comes packed with a micro USB cable that can be removed if necessary—for example, to replace it with a different one. A battery inside allows the unit to run for up to 26 days in standby mode, 10 hours of talk time,or eight hours of music playback. The Cara II also has a dedicated on/off switch, the only one of the pack to offer the feature. However, in a live test against the Himbox, our caller noted an echo of about 1.5 second, meaning he heard his own voice back after he spoke. This is such a serious strike against the system that keeps it from being a top pick, which is a shame, because it’s an otherwise very good product.

The Belkin CarAudio Connect was the worst aux-in kit we tested. Music had noticeable underlying distortion, and sound quality was bad for incoming and outgoing phone calls. In the voicemail test, the quality was even worse: Voicemails sounded echoey and distorted and were almost unintelligible with the windows down.

In a later round of testing, we included another option from Belkin, the Hands-Free Bluetooth Car Kit. The results were far better than what we saw with its more expensive sibling: Streaming audio was much clearer, and voicemails were more intelligible. Voice quality wasn’t the absolute best, though, and it still picked up more wind noise than some of the other units. This Belkin kit is a good one, but without any differentiating features, it doesn’t rise to the top.

Only one of the units we tested, iKross’s A2DP Bluetooth 4.0 Aux 3.5mm Handsfree Stereo Microphone Car Kit, will let you control both volume level and track playback using physical buttons. While both of those features worked well in our testing, the unit’s voice-control activation was unreliable. But the biggest reason this one failed to make the grade was its voice quality: With the car windows down and the vehicle traveling at about 50 mph, voice quality was the worst of the bunch, and it picked up significant wind noise.

We didn’t test the Scosche MotorMouth II, which uses a design similar to that of the SmartMini Aux, as it’s more expensive than other options and has spotty reviews on Amazon (2.5 out of five stars over 70 reviews).

SoundBot’s SB360 is lacking a few key features and earned tepid reviews for its audio quality from our testing panel. It doesn’t have a hardware button that can trigger Siri or Google Now, and it doesn’t support multiple paired devices. We do like the charger it comes with, which provides one 2.4-amp port, one 2.0-amp port, and a 1.0-amp port. But this feature isn’t enough to overcome the SB360’s audio quality and missing features.

Frieq’s Bluetooth 4.0 Hands-Free Car Kit lacks multiple-device support and voice-assistant activation. It also doesn’t sound particularly great on the other end of a phone call, and neither port on the charger it ships with is labeled to indicate how much current it can provide (the company also doesn’t specify the output in the manual).

Griffin Technology has two options, each of which is lacking compared with the competition. The iTrip Aux Bluetooth takes up your car’s accessory-power port without providing additional USB-power ports, and it offers no physical controls. The iTrip Aux, on the other hand, does provide power for your phone, but only through a permanently attached Lightning-plug cable. This makes the iTrip Aux compatible only with iOS devices, cutting off a huge segment of the market for no good reason. If all you have are iPhones, it might be a decent option, but we didn’t test it.

We tried the Mpow Flex 2-in-1 FM Transmitter for the 2016 update to this guide. One tester found the shiny silver design unsightly, and no one liked the quality of the voicemail messages we generated through it.

We previously recommended Mpow’s Streambot Y as the best option for most people. Its FM-streaming quality is great and we like its ease of tuning, but voice quality simply isn’t as good as with our top pick. If voice quality isn’t a major concern, and this one happens to be on sale, it’s a good alternative.

Another of our former top picks is GoGroove’s FlexSmart X3. The base, which plugs into your car’s accessory-power outlet, is attached to a long flexible arm. But the FlexSmart X3 simply didn’t perform as well as the Streambot Y or FlexSmart X2 in our latest round of tests. CNET’s Antuan Goodwin also reviewed this model and awarded it only 2.5 stars, citing its poor auto-scanning and a high-pitched alternator whine (which we didn’t hear in our tests).

As its name suggests, the GoGroove FlexSmart X3 Compact is essentially a slimmed-down version of the FlexSmart X3. Instead of a long, flexible arm connecting its control pod and display to its charger plug, it has a short, rigid-plastic arm. However, the unit we tested would tune only to even-numbered frequencies (for example, 90.2), which don’t exist in the United States. This is obviously a bug, but Amazon reviews indicate that we’re not the only people to experience this issue with the X3 Compact.

The GoGroove SmartMini BT is actually CNET’s Antuan Goodwin’s pick for best FM transmitter. He claims that the auto-scan is superior to that of the full-size X3. But in our tests, it didn’t function any better than the X3 Compact. As with the X3 Compact, the Smartmini BT regularly auto-scanned to even-numbered frequencies. (Amazon reviews again indicate that this is not a one-off occurrence.) Unlike the X3 Compact, the SmartMini BT would occasionally scan to an odd-numbered station, but the the signal was barely strong enough to hear music over the static, much less to make a phone call.

The Belkin CarAudio Connect is significantly more expensive than other FM transmitters, and its Amazon reviews are not very good (2.5 out of five stars over 50 reviews).Speakerphones

Jabra’s Freeway Speakerphone is the closest competitor to the Roadster 2. It has many of the same features, including an FM transmitter, native voice commands, and motion sensors. It even beats the Motorola when it comes to speaker quality, as the Freeway has a much bigger and better-sounding speaker than the Roadster 2. The tradeoff for that better audio quality, however, is size: At 3.8 inches long and 5 inches wide, the Freeway is nearly twice the size of the Roadster 2. That’s too big. Especially considering that it doesn’t have dedicated music playback controls. It relies solely on voice commands for this (you say “play,” “stop,” or “next track”). It also has a worse FM transmitter. Most annoyingly, its voice command handling is very clunky. In order to access your phone’s voice commands, you have to push a button on the speaker and say “phone commands” before you can access Siri or Google Now. I found this extra step annoying—and distracting to do while driving.

Avantree’s Joytune Wireless Bluetooth In Car Speakerphone has a respectable 3.8-star rating on Amazon, but we ruled it out because it offers no voice control prompts: You can’t use Siri or Google Now from the speaker. In all fairness, the feature can still be triggered from the phone itself, but if the idea is to have a solution that doesn’t make you mess with your phone, the Joytune isn’t in. We were also disappointed by the FM transmitter, which kept auto-tuning to frequencies that were already filled by strong stations.

Although it can be had for about half the price of the Roadster 2, Plantronics’s K100 didn’t make the cut. For one, we found it to be less intuitive to use, especially when it comes to activating voice controls. Instead of a dedicated button requiring only a quick press, Plantronics hides the feature in the round multifunction button, centered toward the top—a two-second press triggers your phone’s voice-control system. But the button is also used for powering the unit on and off, redialing, transferring calls to or from the phone, and performing other functions. It also lacks physical buttons for navigating and playing/pausing music. Finally, the Moto offers 20 hours of talk time and three weeks of standby, versus 17 hours and 15 days, respectively, for the K100.

We skipped the Jabra Cruiser 2, which is very similar to the Freeway in terms of features, as we felt the Freeway was superior thanks to its motion sensors, native voice commands, and Bluetooth 3.0.

We also skipped over any speakerphone that didn’t have a built-in FM transmitter, including the BlueAnt S4, SuperTooth HD, SuperTooth Buddy, Jabra Cruiser, IOGear Solar Bluetooth, SuperTooth Crystal, Jabra Drive, Jabra Tour, and Scosche Talkback. We did this because even though we generally aren’t impressed by FM transmitters, we think (given the limitations of speakerphones’ small internal speakers) it’s essential to have the option to play audio through your car’s speakers.

Nick Guy is the accessories writer for The Wirecutter, and covers barware and drinking accessories for The Sweethome. He previously served as accessories editor at iLounge, and wrote about cocktails for Serious Eats. His work has appeared on TIME.com, Fast Company, and Tested.com.

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